HOW TO CHOOSE THE RIGHT FABRIC FOR CLEANROOM APPAREL?

As you decide on the right cleanroom apparel for your controlled environment application, have you ever wondered about the fabric?

What are the fabrics available for cleanroom apparel?

Various types of fabrics are used in the construction of garments and accessories to be worn in cleanrooms and other controlled environment areas. Fabric selection is based on the specific degree of contamination control required in the area and other factors, including cost, comfort, and durability.

Characteristics of fabrics, threads (continuous filament polyester fibers), and other materials used in apparel and accessories may affect the performance of the gowning system. There are three types of fabrics that can be used in the construction of cleanroom garments:

woven
knit
nonwoven

Each type of fabric has specific advantages and disadvantages and is available in a variety of forms. Fabrics chosen for evaluation should be cleanable by available methods and should be compatible with chosen sterilization technology. Fabrics containing natural fibers, such as cotton, linen, and wool are noncompatible cleanroom fabrics. They will shed particles and fibers and should not be used.

Woven fabrics

a) Woven fabric

Woven fabric is any textile formed by weaving. Woven Fabrics used in cleanrooms are normally made from 100% filament polyester or polyester carbon composite fibers to minimize particle shedding and are often used as reusable cleanroom garments, including body coverings, head coverings, and footwear, for use in all classifications of controlled environments.

Woven fabrics are often created on a loom, and made of many threads woven on a warp and a weft. Technically, a woven fabric is any fabric made by interlacing two or more threads at right angles to one another. Woven fabrics are generally more durable. The float of a fabric is determined during weaving. This characteristic is the result of crossing a given number of consecutive vertical strands of yarn with another number of consecutive horizontal strands of yarn (e.g, 1×1, 2 ×1,2×2,3×2, etc.). The float can produce a visual pattern known as the weave design. The weave design not only affects the way a fabric looks but also affects the physical properties of the fabric. Weave design, yarn density, and filament selection play a critical role in determining the following properties of a fabric: Interwoven fabric. Floating can produce a visual pattern called a woven design. Weave design not only affects the appearance of the fabric but also affects the physical properties of the fabric. The fabric design, yarn density, and filament selection play a key role in determining The following properties of The fabric:
thickness,
weight,
flexibility and drape,
hand (feel to the touch),
filtering and barrier properties,
comfort,
strength and durability.

b) Types of weave designs and fabrics

NOTE: Although calendering reduces air permeability, experience has shown a small decrease in MVTR due to calendering when comparing MVTR of the same fabric before and after calendering.

1) Plain weave fabric or taffeta —

plain weave construction and weaving plan

All woven fabric is made using a loom to weave many individual threads (the vertical warp threads and the horizontal weft threads) into a larger whole. The way these threads are woven together determines the fabric’s structure and durability—the simplest and most common type of weave is known as “plain weave“. The most basic of weave designs, in which yarns pass over and under adjacent yarns in a 1 ×1 float pattern. A plain weave is capable of being the tightest, lightest, and thinnest of the fabric weaves. Even tighter weaves may be attained through calendering

2） Twill weave fabric—

Twill weave: Also known as twill fabric, the threads in a twill weave run in a ribbed diagonal pattern. When weaving twill, the weft thread (the horizontal thread) is woven over one or more warp threads (the vertical thread held taught on a loom) and then under one or more warp threads. The fabric surface usually exhibits a diagonal pattern. Common twill floats are 2×1,2 ×2, and 3×2. Longer floats typically allow the fabric to be more flexible and therefore softer to the touch, but usually also cause the fabric to be thicker and have greater permeability. A herringbone weave is a twill variation. Twill and other loosely constructed woven fabrics are recommended for less critical environments.

3) Calendered fabric—

A woven fabric may be calendered by being pressed under high heat and pressure in order to soften and flatten the filaments. The calendering process reduces the space between the filaments, thereby reducing pore size, increasing filtration efficiency, and decreasing permeability. The resultant reduction in permeability, i.e., moisture vapor transmission rate (MVTR), should be assessed，since it may cause discomfort to those wearing the garments.

NOTE: Calendered fabric and laminated fabric are typically used in more critical environments.

c)Special treatments

In controlled environments where electrostatic dis-charge (ESD) is a concern, woven fabrics may contain conductive or static-dissipative monofilament or multifilament yarns in a stripe or grid pattern. In some instances, woven fabrics may also contain durable, topical, chemical finishes designed to provide splash protection, improve soil release, reduce static, control microbial growth.

The end-user must thoroughly evaluate the relative advantages and potential disadvantages of the various treatments or fabric modifications to ensure a selected treatment or modification will not adversely affect the user’s product or process.

Knitted fabrics

Knitted Fabrics are not normally used in cleanrooms. Knit fabrics are generally characterized by their stretch, flexibility, and lightness. however, the innate characteristics of knit fabrics do not provide a stable filtration medium for body-covering garments. Accordingly, ，knit fabrics are not recommended for use in cleanrooms.

Non-wonven fabrics

The third fabric type used in the construction of cleanroom garment systems is nonwoven fabric. Nonwoven fabric is a fabric-like material made from staple fiber (short) and long fibers (continuous long), bonded together by chemical, mechanical, heat, or solvent treatment. The term is used in the textile manufacturing industry to denote fabrics, such as felt, which are neither woven nor knitted.[1] Some nonwoven materials lack sufficient strength unless densified or reinforced by a backing. Nonwoven fabrics are engineered fabrics that may be single-use, have a limited life, or be very durable. Nonwoven fabrics provide specific functions such as absorbency, liquid repellence, resilience, stretch, softness, strength, flame retardancy, washability, cushioning, thermal insulation, acoustic insulation, filtration, use as a bacterial barrier, and sterility.

a) Types of nonwoven fabrics and their uses

1) Spunbond or thermal bond—

A commonly available nonwoven fabric typically made from polypropylene in a relatively open structure and used in bouffant caps, shoe covers, etc. Due to the structure of spun-bond or thermal bond fabrics, this type of nonwoven fabric does not demonstrate high barrier performance,i.e.，high filtration efficiency and splash resistance. Spunbond and thermal bond nonwovens have limited use in the critical environments of the electronics, biotech, and pharmaceutical industries They may provide sufficient barrier properties for some types of medical device manufacturers and other areas where lesser barrier properties are adequate. Spunbond fabrics are made from continuous filaments, which increase strength and reduce lint propagation.

2) Flash spun–

A nonwoven fabric made of high-density poly-ethylene continuous fibers and used for overalls and aprons. Flash spun nonwovens have barrier properties and are splash-resistant to water. Flash spun nonwoven fabric is the most common fabric for disposable cleanroom garments.

3) Meltblown-

A nonwoven fabric made from continuous poly-propylene microfibers and used in composite structures of many types of facemasks because of its high filtration efficiency and repellency. Meltblown nonwoven fabric does not have adequate strength to be used alone for garments.

4) Spunbond/meltblown/spunbond(SMS)–

A laminate (sandwich) structure made from polypropylene continuous fibers and used in coveralls, aprons, etc. SMS fabrics offer barrier properties and comfort and can be used in areas where improved barrier properties are required.

5)Film laminate—-

A spun bond layer laminated to nonporous films. This laminate demonstrates particle, blood, and chemical barrier characteristics, but often lacks air and moisture permeability.

6) Microporous film laminate—

A laminate made from a spun-bond layer and microporous film for improved barrier properties. This laminate is splash-resistant and is a blood barrier. Microporous film laminate is optimal for use in surgical areas and critical environments.

c)Special treatments

Many nonwovens can be sterilized by a variety oftechniques and treated for antistatic properties.

d)Effects of processing

Cleanroom garments made of spun-bonded polyolefin are usually intended for limited use (considered to be disposable). Spunbonded polyolefin garments should be laundered and processed prior to use; however, repeated laundering is not recommended. In addition, spun-bonded polyolefin garments are not compatible with repeated ionizing radiation sterilization techniques because the degradation of physical properties is too great; repeated ionizing radiation results in unacceptable garment degradation (articulation) as well as fabric deterioration (garment tendency to fall apart when donned). Accumulatedionizing radiation sterilization of no greater than approximately 50kG for disposable (one-time-use)garments has been found to be acceptable. Fabrics made of spun-bonded polyolefins may be stabilized with the use of certain additives included during the fiber-forming process in order to provide greater compatibility with the repeated ionizing radiation sterilization process.

Therefore, we say that we need to decide which clean suit to choose according to the cleanliness requirements of the clean room, as well as to understand what fabric the clean suit is made of. You can also consult our sales staff for the best recommendation.

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Jing

Hi, I’m Jing Jiang, the marketing director of midposi.com, I’ve been running in this field in China that supply cleanroom suits for 5 years now, and the purpose of this article is to share with you the knowledge related to cleanroom suits from a Chinese supplier’s perspective.

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HOW TO CHOOSE THE RIGHT FABRIC FOR CLEANROOM APPAREL?